Roadmap
======
The past
--------
First, lets summarise KAS's journey so far.
For details, see the [CHANGELOG](CHANGELOG.md).
### 0.0.x — January 2019
Early releases, built over GTK.
### 0.1.0 — December 2019
A restart, replacing GTK with direct widget implementations including rendering
via the `rgx` crate. Initial theme traits, event-handling revision.
### 0.2.0 — February 2020
Lots of small but significant changes, including the introduction of the
`Manager` handle, user-defined `configure` code, scheduled updates (animation),
a scrollable region with scrollbars and addition of `ToolkitProxy`.
### 0.3.0 — February 2020
Only three weeks later, this delivered two new levels of draw API (portrayed by
`clock` and `mandlebrot` examples respectively), a "flat" theme, run-time theme
and colour-scheme switching, widget alignment, `StretchPolicy`, more adjustments
to event handling (removal of by-coordinate addressing), a `RadioBox` widget,
and window size limits.
### 0.4.0 — May 2020
This release revised widget traits into an integral family with opt-out
derivation (thus allowing future extension without breaking all existing
widgets), separating child-enumeration out of `WidgetCore` and separating
routing and handling of events.
Secondly, the release improved layout generation and notation, adding proper
margins, replacing `Horizontal` and `Vertical` with the four principal
directions, rewriting `solve_seq` to make only required changes (enabling
manual column resizing), and calculating the ideal window size before creation.
Thirdly (and no less significantly), the release added pop-up menus, including
fixes for overlapping graphics and robust event handling (including delayed
opening of sub-menus and navigation via tab and arrow keys).
Fourthly, it added Alt-accelerator keys, including visible labels when Alt is
depressed and locality to the visible pop-up layer.
Small additions included recursive disabled states for all widgets and an error
state for `EditBox` (set via a user-defined input guard). Widgets included a
`Slider`, a resizable `Splitter`, a `ComboBox` and menu widgets.
### 0.5.0 — August 2020
This release focussed on text presentation and editing with a new library,
[kas-text](https://github.com/kas-gui/kas-text/). The text editing experience
has been massively improved, especially for multi-line text, and now supports
bidirectional text, glyph shaping, and all the expected selection, navigation
and editing functionality. Text presentation now supports justified text and
faster re-wrapping when resizing the window.
Some tweaks to input handling and resizing landed, including (unconfigurable)
short-cuts, double-click tracking and separate inner and outer margins.
Additionally, a [CONTRIBUTING](CONTRIBUTING.md) guide and this `ROADMAP`
have been added.
### 0.6.0 — November 2020
A continuation of the work on text, with intial support for rich text,
exemplified via a Markdown parser. Underline and strike-through may be applied
to texts at draw-time, and font adjustments (size, bold/italic and font family)
may be applied as part of text layout.
To allow retrieval of data from temporary (dialog) windows, the
`Window::on_drop` method was added.
This release also simplifies distribution by bundling pre-compiled GLSL shaders.
### 0.7.0 — April 2021
This release focussed on one of the remaining hard problems: data sharing. A new
framework for "view widgets" was introduced, allowing (interactive) views over
shared data.
View widgets enable synchronised access to shared data from multiple locations.
Additionally, by avoiding dedicated widgets for each data item in a set, views
are scalable to large data sets.
Also included are several improvements to sizing, widget construction and event
handling, as well as a new type-conversion library.
### 0.8.0 — June 2021
This release finally addressed one of the most obvious missing features of KAS:
images. At least, in their most basic form: static raster images loaded from
file sources. This new raster-image rendering system was then tweaked and used
as a replacement for the `glyph_brush` library, giving us better control over
glyph rendering and caching, and allowing a choice of font glyph rasterer.
The work on fonts and text did not stop there: as part of KAS-text 0.3, the
(rather large and mostly unused) dependency `font-kit` was replaced with
`fontdb` (plus a collection of custom aliases), extended to support font
fallbacks and run-time configuration, meanwhile `rustybuzz` was integrated as
a pure-Rust alternative to HarfBuzz for text shaping. These changes removed
all non-Rust dependencies from the text system.
Partially related to the above was the work on theme configuration, covering
colour schemes, font size, font family (per font class and global), and glyph
rastering.
### 0.9.0 — August 2021
Following the recent addition of image support, this release takes the
opportunity to revise the draw API, culminating in a new unified `Draw` trait
and `DrawIface` implementation, accessible via `DrawHandle::draw_device`. This
simplifies usage of mid-level draw APIs, e.g. in themes and the `clock` example.
Also in this release is SVG support, a `Canvas` widget, image buttons, and
fixed sub-pixel positioning (clearer rendering for small text).
### 0.10.0 — September 2021
This release responds to three key criticisms of KAS: (1) slow compile times,
(2) non-standard keyboard navigation, (3) ugly themes. While these issues are
not fully solved, they are significantly improved. Additionally,
the latest version of WGPU now gives us a working OpenGL backend.
Future work
-----------
These items are not versioned and appear only roughly in the expected order.
Each should be a decently sized work item (roughly one release).
### Standard geometry types
KAS has ad-hoc geometry types. *Possibly* it would be useful to use third-party
types instead. See [#95](https://github.com/kas-gui/kas/issues/95).
### Images and icons
Support display of images in the GUI:
- image display using a target size and multiple rastered versions, with
the option of scaling to the target size or using the nearest size
Possibly as part of this topic, implement colour management
[#59](https://github.com/kas-gui/kas/issues/59).
### Standard resource sets
Ideally, KAS should provide an identifier for common icons and either map these
to a system-provided icon set or provide its own, so that apps can use icons
like "save" or "undo" without having to provide the icon themselves.
Colour schemes and short-cuts are similar in that potentially they can be
inherited from the desktop, but otherwise KAS should provide them.
### Context menu and undo
KAS supports pop-up menus since 0.4. Context menus are a little different, in
that the widget opening the menu does not own it, yet can still customise it
(enabling or disabling items like undo, paste, perhaps providing custom items,
perhaps selecting a special context menu).
At the same time, the undo history should probably be removed from widgets and
stored in some shared state.
Slightly related to this is support for global and standard shortcuts such as
undo, copy selection, save file, quit app.
### Script-driven UIs
So far, KAS only supports statically defined widgets and (more limited, without
event handlers) programmatically added widgets. We should aim to support
script-driven UIs: support all layouts with dynamic containers, add direct
integration with a Rust-centric scripting language for building UIs, and add
support for event handlers using dynamic typing.
This should aim both to allow rapid prototyping of UIs and to make KAS easier
to use (especially for those less familiar with Rust's traits, generics and
macros).
### Widget identifiers
Currently widgets are identified simply by enumerating all widgets. See
[#91](https://github.com/kas-gui/kas/issues/91).
### Widget library
Although the current widget set covers a good portion of the "full complement"
mentioned by [#2](https://github.com/kas-gui/kas/issues/2), its primary purpose
is to prototype requirements for other APIs
(including the widget trait family, event handling, draw model).
Once other APIs are more stable, this focus should shift to providing the full
complement of standard GUI widgets, likely within a dedicated crate.
Additionally, several standard dialog boxes / pop-ups should be added, e.g. a
colour picker, a date picker, and a file-open dialog.
### Desktop integration
This is less a separate work item than it is a long-term goal, one which will
require substantial help. KAS should attempt to discover initial configuration
from the current desktop environment, e.g. the current font and font size, the
icon set, locale and short-cuts.
Additionally, on Linux it is expected that the desktop environment provide a
few standard dialog boxes (e.g. file open/save), not only for consistency but
also security (e.g. a container may not let an app explore the filesystem).
Such dialogs should automatically use desktop-provided equivalents where
available.
External dependencies
----------------------
### WebGPU and CPU rasterisation
Currently, KAS can only draw via `wgpu`, which currently does not support OpenGL
or CPU-rendered graphics, making KAS unusable on many older systems.
It seems likely that `wgpu` will support OpenGL in the future.
Additionally, KAS should provide a CPU-based renderer. See
[#33](https://github.com/kas-gui/kas/issues/33).
### Clipboard support
We have plain text clipboard support via
[window_clipboard](https://github.com/hecrj/window_clipboard), but lack support
for formatted text, images, etc.
### (winit) pop-up window support
It has been requested that winit support popup windows for things like menus
which are not restricted to the parent window; currently it doesn't.
See [winit#950](https://github.com/rust-windowing/winit/issues/950) (and other
issues).
### (winit) drag and drop
Winit *does* have support for this, but only in a very limited fashion. With
its current event model it is difficult or impossible to determine the widget
receiving a drop or under a hovered drop.
See [#98](https://github.com/kas-gui/kas/issues/98) and
[winit#1550](https://github.com/rust-windowing/winit/issues/1550).
### (winit) key-bindings and text input
This needs revision, allowing more generic key bindings and supporting Input
Method Editors (IME). Winit has an on-going effort here which will require
support in KAS: <https://github.com/rust-windowing/winit/issues/1806>.